Most behaviors arise from complex interactions between distant anatomical areas. These areas receive neural information asynchronously in time. To investigate behavior while still maintaining the timing of information that occurs during real sensory stimulation, an external stimulation system with reasonable spatio-temporal resolution is needed. Current trans-cranial magnetic stimulation (TMS) technology is limited to single brain regions. The goal of the proposed research is to develop a novel TMS system based on multi-channel reconfigurable coils. With this hardware, researchers will be able to reproducibly stimulate multiple brain sites in any temporal order-in the same experiment and on a single experimental trial. This design has applications in basic neuroscience. We also anticipate that the dynamic TMS could be useful to treat mood disorders and other psychiatric problems. The proposed system will employ a wire-mesh coil, which will be constructed using several x-directional wires and several y-directional wires. By varying the current direction and/or strength on each wire, we can configure this mesh-wire coil into a standard loop coil and figure-8 coil of varying size. This provides maximum flexibility to the experimenter in that the location and extent of stimulation on the brain surface can be modified depending on experimental requirement. Moreover, one can dynamically and automatically modify the site(s) of stimulation several times within the span of seconds. By pre-storing various sequences of excitation patterns inside a control unit, one can explore the effect of dynamic TMS on behavior and as therapy. The specific objectives are: 1. To develop a prototype dynamic TMS device containing reconfigurable coils. 2. To test the ability of the reconfigurable coils to deliver focused magnetic fields of sufficient strength to selectively excite or inhibit selected brain regions in a phantom model. 3. To assess the safety and failure modes of the system. PUBLIC HEALTH RELEVANCE: We will develop a novel Transcranial Magnetic Stimulator (TMS) coil that can dynamically and automatically modify the site(s) of stimulation several times within the span of seconds.